4005-51-0

64-18-6

79-19-6

4005-51-0

General procedure for the synthesis of 2-amino-1,3,4-thiadiazole from formic acid and aminothiourea: 5.00 g of aminothiourea was accurately weighed and placed in a 50 mL three-necked flask fitted with a stirring magnet, and 5.00 mL of formic acid was added at once. The reaction was stirred under the condition of cooling in an ice bath, and after the formation of a slurry, 6.00 mL of concentrated hydrochloric acid was added slowly and dropwise. After the dropwise addition, the reaction mixture was transferred to an oil bath preheated to 107 °C with stirring turned on and the reaction was carried out for 4.5 to 5.0 h. During this time, the reaction progress was monitored by thin-layer chromatography (TLC), and the reaction was stopped when the raw material point disappeared. After the reaction solution was cooled to room temperature, the pH was adjusted with concentrated ammonia to 8-9. The mixture was placed in a refrigerator overnight, white crystals were precipitated, filtered, washed three times with ice water, and finally recrystallized with distilled water to give 4.96 g of white crystal product in about 90% yield. The melting point of the product was 198 to 201 °C. The resulting product was confirmed to be 2-amino-1,3,4-thiadiazole by infrared spectroscopy (IR), nuclear magnetic resonance (NMR) and mass spectrometry (MS) analysis.